Compressor with counterweight means

ABSTRACT

A compressor for automobile air conditioning systems of the type having a dual action piston which is reciprocal within a cylindrical bore extending normal to a rotatable drive shaft. A slider block which is supported within a cavity in the piston has an irregularly shaped bore therethrough including a number of circumferentially spaced large radius portions which are adapted to be engaged by lobes on a cammed portion of the drive shaft to cause the slider block to reciprocate both laterally within the piston cavity and move with the piston in the cylinder. Located adjacent the slider block in the piston cavity is a counterweight having an irregular bore therethrough similar to the bore in the slider block but with the angular orientation of the large radius portions shifted to cause the counterweight to move in an opposite direction to the slider block and to the reciprocating piston when the drive shaft is rotated.

United States Patent 1191 FOREIGN PATENTS OR APPLICATIONS" 4,382 6/1911 Great Britain 74/55 8 Zit Jacobs Apr. 23, 197 4 COMPRESSOR WITH COUNTERWEIGHT MEANS Primary Examiner-William L. Freeh Assistant Examiner-Arnold F. Ward [75] Inventor: James W. Jacobs, Dayton, Ohio 7 Attorney, Agent or H MacLean Jr. [73] Assignee: General Motors Corporation, 1

I lDetro1t, Mich. 57] ABSTRACT [22] Filed: 1973 A compressorfor automobile air conditioning systems [2]] App]. No.: 339,330 of the type having a dual action piston which is reciprocal within a cylindrical bore extending normal to a 52 us. c1 417/534, 417/534, 74/55 f bkck [51] Int Cl F04}, 21/02 F1611 25/08 F16h 25/16 7 ported within a cavity in the piston has an irregularly H 58 Field of Search ..'417/404, 534,525, 533, shaped f herethmugh t a p 417535437 74/590 591 573 cumferennally spaced large radius pornons which are 7 567 9 adapted to be engaged by lobes on a cammed portion I of the'drive shaft to cause the slider block to reciprocate both laterally within the piston cavity and move [56] References Cmd with thetpiston in the cylinder. Located adjacent the UNITED STATES PATENTS slider block in the piston cavity is a counterweight 1,631,425 6/1927 Marc us. 417/273 having an irregular bore] therethrough similar to the 3,307,430 1967 p 418/32 bore in the slider block but with'the angular orientag 2/1966 Hub?" tion of the large radius portions shifted to cause the gfigs counterweight to move in an opposite direction to the 2:840:99l 7/1958 Nisbetiiiii .1. 60/452 Slide block and recipmcafing g w the drive shaftis rotated.

Claims, 11 Drawing Figures PATENTEUAPR 23 1974 I SHEET 3 OF 3 compressors and more particularly to counterweight means to smooth out forces produced by the shifting masses of thepiston and drive means within the compressor.

In piston type compressors having only one or two pistons, the mass of the piston moving within the cylinder and the shifting of drive means used to reciprocate the piston causes cyclic forces. This causes vibration of the compressor. Although these compressors are simpler and more economical to manufacture than multipiston compressors, vibrational problems have limited their use in automobile air conditioning systems. To avoid these vibrations, automobile manufacturers have utilized multi-piston compressors which smooth out vibrations. However, the multi-piston compressors are more complex and are expensive.

The present compressor includes a single dual-ended piston supported within a cylinder bore of a housing. The piston is reciprocated within the cylinder by rotation of a cammed drive shaft which extends through a bore a slider block within the piston. More particularly, the slider block is mounted withina cavity to permit lateral reciprocation of the slider block in the piston. The slider block has an irregularly shaped bore therethrough with alternating large and small radius portions spaced circumferentially. A cammed portion on the drive shaft extends through the slider block and has a number of outwardly extending lobe portions adapted to engage the irregular shaped portions in the slider block. Rotation of the cammed portion causes the slider block to reciprocate laterally with respect to the piston and to also reciprocate the piston within the cylinder.

A counterweight is supported around the cam portion of the. drive shaftand adjacent the slider block. It has an irregular bore therethrough similar tothe bore in the slider block but with the radial portions angularly shifted to cause the counterweight to move oppositely to ,the slider block and the piston. This movement counteracts forces produced by the change in motion of the slider block and piston.

The bores in the slider block and the counterweight haveone extra outwardly extending large radius portion that the number of radially directed lobes on the cammed portion of the drive shaft. This produces multiple reciprocation of the piston within the cylinder bore and lateral movement of the slider block and counterweight in the piston. The number of lobe portions on the drive shaft determines the number of reciprocations of the piston per revolution of the drive shaft.

An object of the present invention is to provide an inexpensive and compact compressor of the reciprocating piston type having a slider block mounted within a cavity in the piston for lateral movement therein and having an irregular bore therethrough operably engaging a cammed portion of a drive shaft to cause reciprocation of the piston and lateral movement of the slider block as the drive shaft is rotated.

A further object of the present invention is to provide a smooth operating compressor having a piston reciprocated in a cylinder by engagement of a'cammed por tion of a drive shaft witha slider block mounted in the piston and also having a counterweight engageable with the cammed portion to produce motion opposite in dicammed portion;-

2 rection to the slider blo'ck for'minimizing vibrations caused by shifting of the slider block.

A still further object of the present invention is to tion will be more readily apparent from the following detailed description, reference being had to the accompanying drawings which clearly show a preferred embodiment. IN THE DRAWINGS FIG. I is a vertical sectioned view of the present compressor;

FIG. 2 is a sectioned view of the compressor taken along section line 2-2in FIG. 1 and looking in the direction of the arrows;

FIG. 3 is a sectioned view of the compressor similar to FIG. 2 but with the drive shaft rotated 30;

1 FIG. 4 is a sectioned view similar to FIG. 2 but with the drive shaft rotated 60;

FIG. 5 is a perspective view of the drive shaft with its 'FIG. 6 is a perspective view of the counterweight in FIG. 1;

FIG. 8 is a sectioned view taken along section line 88 in FIG. 1 and looking in the direction of the arrows;

FIG. 9 is a sectioned view similar to FIG. 8 but showing the drive shaft rotated 30 from the position shown in FIG. 8;

FIG. 10 is a sectioned view similar to FIG. 8 but showing the drive shaft rotated from the position shown in FIG. 8; and

FIG. 11 is a sectioned view similar to FIG. 8 of the compressor illustrating other means to prevent rotation of the counterweight with the'cammed portion of the drive shaft.

In FIG. 1 of the drawings, a compressor 10 is illustrated. Compressor 10 includes a housing 12 which has a cylindrical bore 14 therein. Bore 14 supports a dualended piston 16 for reciprocation in the housing. Compression chambers 18, 20 are formed at either end of piston 16 by the cylinder bore 14 and cover members A drive shaft 38 is supported for rotation within housing 12 by bearing assemblies 40, 42. The bearing 42'is located within the referigerant inlet 44 of cornpressor 10. An inlet fitting (not shown) is adapted to engage the end 46 of housing 12 to connect a fluid conducting conduit to the compressor. An O-ring 48 prevents refrigerant leakage between the housing 12 and the inlet fitting. The other end of drive shaft 38 is supported by needle bearing 40 and further extends through a seal assembly 50. A threaded end portion 52 is adapted to secure a pulley (nt shown) to the drive shaft 38. The seal assembly includes a stationary ring 54 which encircles the drive shaft 38 and is attached to the housing 12 by an expansion ring 56. An O-ring 58 between the stationary ring 54 and the housing 12 prevents refrigerant leakage around the seal assembly 50. A rotating ring 60 is pressed into engagement with the stationary ring 54 by a compression spring 62 which is attached for rotation with the drive shaft 38 by a retainer 64.

The mid-portion of drive shaft 38 extends through a cut-out portion or cavity 66 and also in the piston 16 through openings 68 and 70.

A rectangular slider block 72 is supported in cavity 66 and is free to reciprocate in a lateral direction normal to the axis of the piston 16 while engaging the upper and lower walls 74 and 76 of the piston 16 to move the piston up and down in cylinder 14. The slider block 72 has an irregularly shaped bore 78 therethrough as best shown in FIG. 2. The bore 78 consists of alternate large radius portions 80 and smaller radiusportions 82. In the particular embodiment illustrated, the bore 78 has four symmetrically spaced larger radius portions 80. The radial portions 80 of bore 78 are adapted to be engaged by outwardly extending lobe portions 84 of a cammed mid-portion 86 on drive shaft 38. When the drive shaft 38 is rotated clockwise in FIG. 2, the lobes 84 engage the portions 80 of bore 78 to cause the slider block to reciprocate laterally first to the right and then to the left as illustrated in FIGS. 2-4. Simultaneously, the piston 16 is reciprocated in an up and down movement within the cylinder bore 14 as shown in the same figures. FIGS. 2-4 illustrate the clockwise rotation of drive shaft 38 in increments. Rotation of 60 moves the piston halfway through a complete up and down cycle.

Reciprocation of piston 16 causes refrigerant to be drawn through inlet 44 and central passage 88 in the drive shaft 38 to an interior space 90 and thereafter into the cavity 66. From cavity 66,'refrigerant flows through a number of inlet ports 92 best shown in FIG. 2 and past leaf-type inlet valves 94 into the compression chambers 18 and 20. The refrigerant is compressed within the chambers 18 and 20 and is discharged through outlet ports 96 in members 22, 24 and past annular leaf-type outlet valves 98 to an outlet cavity 100. The refrigerant then flows through an outlet fitting attached to the compressor (not shown).

When the drive shaft 38 is rotated, the lobes 84 on the cammed portion 86 engage the large radius portions 80 of the irregular bore 78 in the slider block 72. This causes the slider block 72 to laterally reciprocate within cavity 66 of piston 16 and produces reciprocal movement of the piston 16 within the cylinder bore 14.

' As illustrated in FIGS. 2-4, the piston 16 reciprocates up and down within cylinder 14 once for each third of a revolution of the drive shaft 38. In FIG. 2, the piston 16 is at its lowermost position with lobe 84 directed vertically upward. In FIG. 3, the lobe 84 has been rotated 30 from the position in FIG. 2 and the slider block 72 has been moved laterally to the right while the piston 16 has been moved upward within the cylinder 14. This compresses refrigerant in comprespermost vertical position completing the compression stroke in chamber 18 and the intake stroke for compression chamber 20. Rotation of the drive shaft 38 to move the lobe 84' another 60 causes the slider block to be shifted to its extreme left position and then back to its mid position and causes the piston to move 'fully downward for the compression stroke of chamber 20. Thus, for every 120 rotation of the drive shaft 38, the piston is moved upward and downward through a complete power cycle.

The refrigerant enters the compressor through inlet 44 and passes then through the axial passage 88 and radial passage 89. Another passage 101 continues axially through the drive shaft 38 to a port 104 which inter sects cavity 102 in which the seal assembly 50 is housed. This provides a flow of refrigerant to the seal to lubricate the seal and prevent undue wear between the stationary ring 54 and the rotative ring 60. The flow of lubricant to the cavity 102 also supplies oil to bearing assembly 40.

Because both the slider block 72 and the piston 16 are reciprocated three times for each revolution of drive shaft 38, considerable inertial forces are generated by the cyclic acceleration and deceleration of the members. These forces may produce undesirable cyclic vibrations in the compressor. The subject compressor includes means which oppose the inertial forces produced by the reciprocating slider block and piston. A

ing larger radius portions of bore 78 in slider block 72. This produces movement of the counterweight 106 opposite to the movements of the slider block 72 as is best shown in FIGS. 8-10.

In FIG. 8, the uppermost lobe portion 84 of the cammed portion 86 is shown in the same position as in FIG. 2. At this position of lobe 84', the counterweight 106 is at its uppermost position and is centered with respect to the axis of the drive shaft. As the drive shaft 38 is rotated and lobe 84' moved 30 to the position shown in FIG. 9 (which corresponds to the position of the slider block in FIG. 3), the counterweight 106 is shifted downward and to the left which is opposite to the movement of the slider block 72 and piston 16 (as illustrated in FIG. 3). When the lobe 84' is rotated another 30 to the 60 position shown in FIG. 10 (corresponds to FIG. 4), the counterweight 106 is moved further downward and to the right to a central position. This movement is in opposition to the movement of the slider block toward the left and upward with the piston as shown in FIG. 4.

- As best seen in FIGS. 8-10, the counterweight 106 is moved in an oscillatory path about the axis of the drive shaft. Interference with the top and bottom end walls 74, 76 of piston 16 and with side walls of the piston will prevent the counterweight from rotating with the drive shaft. The slightclearance between counterweight 106 and the piston will, however, permit a slight rotative oscillation of the counterweight about its axis. This should be of minor consequence and should not affect compressor smoothness.

The embodiment shown in FlG. 11 includes means to prevent the slight oscillatory movement of counterweight 106 about its axis. Specifically, the counterweight is provided with arms 1 l4 and 116 which extend from opposite sides of the counterweight. The outer end 118 of arms are pivotally fastened by pins 120 to an anti-rotation crank '122 which is supported in cylindrical recesses 124 of housing 12. The ends 118 of arms 1 14, 116 are attached to cranks 122 at a location offset from the axis of cranks 122 a distance A equal to half the total vertical displacement of counterweight 106.

When drive shaft 38 is rotated clockwise, the lobes 84' 7 cause the counterweight to move in a counterclockwise orbital path. Rotation of the cranks 124 causes arms 114, 116 to guide the counterweight 106 in pure orbital movement which eliminates any rotation of counterweight 106 about its own axis.

While the embodiments illustrated are preferred, other embodiments may be adapted without departing from the scope of this invention claimed as follows.

What is claimedis as follows:

l. A compressor comprising a housing supporting a drive shaft for rotation therein which extends through the intrior of the housing; said housing having a cylindrical bore therein with an axis extending substantially normal to the drive shaft; adual-ended piston supported for reciprocation in said cylindrical bore; said piston having a cavity formed in its mid portion through,

which said drive shaft extends; a cammed portion on said drive shaft extending through said piston cavity and having circumferentially spaced and radially outwardly extending lobes formed thereon; a slider block mounted within said piston cavity for reciprocation therein in a lateral direction with respect to the axis of the piston and cylinder bore; an irregular bore through said slider block adapted to encircle said cammed portion and having alternate large and small radius portions; said large radius portions adapted to be engaged byjsaid-lobe portions on said drive shaft; said bore in said slider block having at least one more large radius portions than the number of lobes on said cammed portion to permit said cammed portion to be rotated in said bore for producing simultaneous movement of said slider block laterally within said piston cavity and movement of said piston in said cylindrical bore; inlet means including said piston cavity and ports in said piston extending to compression chambers located at the ends of said piston for introducing fluid; a counterweight within said piston cavity and-having an irregular bore identical in shape to the bore in said slider block; said larger radius portions in said counterweight being angularly shifted with respect to the same portions in said slider block bore to produce rotation of said counterweight oppositely to movement of said slider block whereby inertial forces created by the movement of said counterweight.

2. A compressor comprising a housing supporting a drive shaft for rotation therein which extends through the interior of the housing; said housing having a cylindrical bore therein with an axis extending substantially normal to the drive shaft; a dual ended piston supgreatly 6 ported for reciprocation in said cylindrical bore; said piston having a cavityformed in its mid portion through which said drive shaft extends; a cammed portion on said drive shaft extending through said piston cavity having three circumferentia lly spaced and radially outwardly extending lobes formedthereon; a slider block mounted within said piston cavity for reciprocation therein in a lateral direction with respect to the axis of the piston and cylindre bore; an irregular bore through said slider block adapted to encircle said cammed portion and having four larger radius portions spaced circumferentially therein adapted to be engaged by said lobe portions on said drive shaft to permit said cammed portionto be rotated in said irregular bore for producing simultaneous movement of said slider block laterally within said piston cavity and movement of said piston in said cylindrical bore; inlet means including said piston cavity and ports in said piston extending to compression chambers located at the piston ends for introducing fluid; a counterweight within said piston cavity and having an irregular bore identical in shape to the bore in said slider block; said larger radius portions of said counterweight bore being angularly shifted 45 with respect to the same portions in said slider block bore so as to produce rotation of said counterweight oppositely to movement of said slider block whereby inertial forces created by the shifting of said piston and slider block are opposed by the opposite inertial forces created by the. movement of said counterweight.

3. A compressor comprising a housing supporting a drive shaft for rotation therein which extends through the interior of the housing; said housing having a cylin-, drical bore therein with an axis extending substantially normal to the drive shaft;a dual ended piston supported for reciprocation in said cylindrical bore; said piston having a cavity formed in its mid portion through which said drive shaft extends; a cammed portion on said drive shaft extending through said piston cavity and having circumferentially spaced and radially outwardly extending lobes formed thereon; a slider block mounted within said piston cavity for reciprocation therein in a lateral direction with respect to the axis of the piston and cylinder bore; an irregular bore through said slider block adapted to encircle said cammed portion and having four larger radius portions spaced circumferentially therein'adapted to be engaged by said lobe portions on said drive shaft to permit said cammed portion to be rotated in said irregular bore for producing simultaneous movement of said slider block laterally within said piston cavity and movement of said piston in said cylindrical bore; inlet means including said piston cavity and ports in said piston extending to compression chambers located at the piston ends for introducing fluid; a counterweight within said piston cavity and having an irregular bore identical in shape to the bore in said slider block; said larger radius portions of said counterweight bore being angularly shifted 45 with respect to the same portions in said slider block bore so as to produce rotation of said counterweight oppositely to movement of said slider block whereby inertial forces created by the shifting of said piston and slider block are opposed by the opposite inertial forces created by the movement of said counterweight; means including outwardly extending arms on opposite sides of said counterweight whose outwardmost ends are pivotally connected to cranks to cause said counterweight to move about said cammed portion as said drive shaft is rotated in purely orbital movement without rotation of said counterweight about its own axis. 

1. A compressor comprising a housing supporting a drive shaft for rotation therein which extends through the intrior of the housing; said housing having a cylindrical bore therein with an axis extending substantially normal to the drive shaft; a dualended piston supported for reciprocation in said cylindrical bore; said piston having a cavity formed in its mid portion through which said drive shaft extends; a cammed portion on said drive shaft extending through said piston cavity and having circumferentially spaced and radially outwardly extending lobes formed thereon; a slider block mounted within said piston cavity for reciprocation therein in a lateral direction with respect to the axis of the piston and cylinder bore; an irregular bore through said slider block adapted to encircle said cammed portion and having alternate large and small radius portions; said large radius portions adapted to be engaged by said lobe portions on said drive shaft; said bore in said slider block having at least one more large radius portions than the number of lobes on said cammed portion to permit said cammed portion to be rotated in said bore for producing simultaneous movement of said slider block laterally within said piston cavity and movement of said piston in said cylindrical bore; inlet means including said piston cavity and ports in said piston extending to compression chambers located at the ends of said piston for introducing fluid; a counterweight within said piston cavity and having an irregular bore identical in shape to the bore in said slider block; said larger radius portions in said counterweight being angularly shifted with respect to the same portions in said slider block bore to produce rotation of said counterweight oppositely to movement of said slider block whereby inertial forces created by the movement of said counterweight.
 2. A compressor comprising a housing supporting a drive shaft for rotation therein which extends through the interior of the housing; said housing having a cylindrical bore therein with an axis extending substantially normal to the drive shaft; a dual ended piston supported for reciprocation in said cylindrical bore; said piston having a cavity formed in its mid portion through which said drive shaft extends; a cammed portion on said drive shaft extending through said piston cavity having three circumferentially spaced and radially outwardly extending lobes formed thereon; a slider block mounted within said piston cavity for reciprocation therein in a lateral direction with respect to the axis of the piston and cylindre bore; an irregular bore through said slider block adapted to encircle said cammed portion and having four larger radius portions spaced circumferentially therein adapted to be engaged by said lobe portions on said drive shaft to permit said cammed portion to be rotated in said irregular bore for producing simultaneous movement of said slider block laterally within said piston cavity and movement of said piston in said cylindrical bore; inlet means including said piston cavity and ports in said piston extending to compression chambers located at the piston ends for introducing fluid; a counterweight within said piston cavity and having an irregular bore identical in shape to the bore in said slider blOck; said larger radius portions of said counterweight bore being angularly shifted 45* with respect to the same portions in said slider block bore so as to produce rotation of said counterweight oppositely to movement of said slider block whereby inertial forces created by the shifting of said piston and slider block are opposed by the opposite inertial forces created by the movement of said counterweight.
 3. A compressor comprising a housing supporting a drive shaft for rotation therein which extends through the interior of the housing; said housing having a cylindrical bore therein with an axis extending substantially normal to the drive shaft; a dual ended piston supported for reciprocation in said cylindrical bore; said piston having a cavity formed in its mid portion through which said drive shaft extends; a cammed portion on said drive shaft extending through said piston cavity and having circumferentially spaced and radially outwardly extending lobes formed thereon; a slider block mounted within said piston cavity for reciprocation therein in a lateral direction with respect to the axis of the piston and cylinder bore; an irregular bore through said slider block adapted to encircle said cammed portion and having four larger radius portions spaced circumferentially therein adapted to be engaged by said lobe portions on said drive shaft to permit said cammed portion to be rotated in said irregular bore for producing simultaneous movement of said slider block laterally within said piston cavity and movement of said piston in said cylindrical bore; inlet means including said piston cavity and ports in said piston extending to compression chambers located at the piston ends for introducing fluid; a counterweight within said piston cavity and having an irregular bore identical in shape to the bore in said slider block; said larger radius portions of said counterweight bore being angularly shifted 45* with respect to the same portions in said slider block bore so as to produce rotation of said counterweight oppositely to movement of said slider block whereby inertial forces created by the shifting of said piston and slider block are opposed by the opposite inertial forces created by the movement of said counterweight; means including outwardly extending arms on opposite sides of said counterweight whose outwardmost ends are pivotally connected to cranks to cause said counterweight to move about said cammed portion as said drive shaft is rotated in purely orbital movement without rotation of said counterweight about its own axis. 